Question

among the four mechanisms of materials strengthening.Which of these strengthening mechanisms can or can not be used where creep strength is a major cocern? Why?

Answer 1

Grain-Boundary Strengthening

• T <0.5Tm: GBs act as barriers to disln. motion.

• Compatibility of deformation in neighboring

grains necessitates multiple slip (the operation of

5 independent slip systems) and hence high strain

hardening rate.

• T>0.5Tm: GBs provide for higher rate diffusion paths. Results in faster creep.

• At high temps. Grain boundary sliding is another possible mechanism for enhanced creep.

• GBs lead to texture and associated affects.

So Grain Boundary hardening should not be used for creep strengthening.

Where as all other 4 method listed below can be used for creep strengthening:-

1) strain hardening

2) solute atoms -- solid solution strengthening

3) precipitates -- precipitation hardening

4) dispersoids -- dispersion strengthening